Hardrive Out

I am new to this forum and was wanting to find out something about my old computer. Sorry if this thread is in the wrong place.
First off my machine:
Powerbook G4 17- aluminum
1.5GHz/512MB/80G/Superdrive

My hard drive has gone out and I am going to order a new one that is the same as the stock one and remove and install a new one. Once this is done will I need to get OSX from someone? I have a friend that is a mac programer and I can get an OSX from him. Is it hard to install? Will I be able to do this all on my own? I found a step by step video to help me remove and install a new hard drive. Is this all I need to do to make my old computer work?